RE: bhyve GPU passthrough + romfile

Hi John,

first of all, the ROM is only required for Linux/BSD amdgpu driver. Windows works without a ROM file. Additionally, the ROM is required for pre-OS graphics (e.g. EFI boot, bootloader, etc.).

Currently, OVMF doesn't processes the ROM file. Processing the ROM would include:
- executing the ROM
- shadowing the ROM

The amdgpu driver searches for the shadowed ROM. So, for Linux/BSD guest, a patched OVMF is required. If you like to try a patched OVMF, please apply following commits to BhyveX64.dsc:
https://github.com/Beckhoff/edk2/commit/bed77d4bb374fa6450fa2781eeddfbc3604edf6a
https://github.com/Beckhoff/edk2/commit/aeaa9c4c1d1222723cbf9c1c7dd7f5ff3911deac
https://github.com/Beckhoff/edk2/commit/a7b01394682874508d65c6f4b5815cdbb6c6eb6c

As said, Windows requires no ROM. So, that's not the issue. For many years AMD GPUs have issues to reset themselves. It's a well known hardware bug. You didn't mention which AMD GPU your using so I can't check if your GPU is affected too. A possible workaround is descripted at:
https://curtisshoward.com/post/fixing-amd-gpu-passthrough-reset-issues-in-windows/

Btw: On Linux there's some work to solve the GPU reset bug by hardware specific reset routines (https://github.com/gnif/vendor-reset) but I don't think that such kind of work will be merged soon into FreeBSD.

> PS: Is there a known/supported way to get a GPU ROM file from FreeBSD? The one I have I obtained from a Linux host where this GPU was secondary.

No, there's no known/supported way yet. The best way is to boot another OS.


Best regards
Corvin

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